A knight was a professional heavy cavalry soldier in the Middle Ages. They were the top soldiers to the kingdom, and protected it at all costs. Knights worked for lords, who in exchange would give them land if the knight would fight for them. Knights thought honour was very important, and they had a code of honour called chivalry. They always had a coat of arms, also called a crest.
Knights of the Commonwealth Realms today are named by the Sovereign One of the British orders of knighthood is known as the Order of the British Empire. These knights today are called 'Sir' and then their first name. Many members of nobility are descended from knights. For example: Wijerd Jelckama descended from a knight who died at the siege of Antioch (1199).
Knights were first used in the 4th century in the late Roman armies. The era of the knights ended in the 16th century as national armies replaced feudal armies. Many knights were recruited as officers in the new armies. Today's officer corps in all Western armies are direct descendants of knights.